1) $f : X \to Y$ is a map. For all $x_0\in X$, if for every $\delta > 0$, there is $\varepsilon > 0$ such that $d_X(x_0, x) < \delta$ whenever $d_Y(f(x_0), f(x)) < \varepsilon$.
2)$f : X \to Y$ is a map. For all $x_0\in X$, if for every $ \varepsilon> 0$, there is $\delta > 0$ such that $d_Y(f(x_0), f(x)) < \delta$ whenever $d_X(x_0, x) < \varepsilon$.
Is map $f$ continuous in the two cases? If not, what kind of continuity is this?
For the second the case, I guess this definition is much stronger than continuity?